The invention relates generally to an apparatus and a method for friction surfacing, and in particular to an apparatus and a method for friction surfacing using a consumable pin tool.
Friction stir welding is a solid-state joining technique that is well known to those of ordinary skill in the art. Typically, friction stir welding is used to join difficult-to-weld metals, metal alloys (such as aluminum alloys, titanium alloys, nickel alloys, and the like), and other materials. For example, certain aluminum alloys are sensitive in a plasticized heat-affected zone, where the base metal reaches temperatures between solidus and liquidus during welding. In this zone, partial melting at grain boundaries forms a network containing brittle compounds. As a result, weld ductility is substantially reduced.
Friction stir welding is not to be confused with friction surfacing. In friction stir welding, a pin tool is plunged into a rigidly clamped workpiece and traversed along the joint to be welded. As the pin tool is traversed along the joint to be welded, the two materials are joined by way of frictional heating and plasticizing the workpiece with a pin tool, and mechanical mixing (stirring) material from the leading edge of the pin tool to the trailing edge of the pin tool.
By contrast, in friction surfacing, frictional heating plasticizes a consumable pin tool, which is forged onto the substrate surface. In friction surfacing, there is no mechanical mixing (stirring) between the workpiece material and the deposit material.